1. Field of the Invention
The present invention relates to a surface shape determining device.
2. Description of the Related Art
Generally, in a machine tool, a work is supported by an upper face of a bed via a work supporting table and the work is worked by a tool mounted to a main spindle device numerically controlled to move respectively in three axes directions of X, Y, Z axes similarly on the upper face of the bed. For measuring a position in a Z axis direction of the main spindle device, there are various methods of using, for example, measurement of length by laser, a proximity sensor or a touch sensor or the like. In measuring a displacement by using the sensors, reliability against resistance to environment, adverse environment as in in-line operation, coolant mist, chip or a change in temperature is poor, and there poses a problem of, for example, reading an error, a temperature drift or biting a chip or the like.
In order to resolve the above-described problem, a position detecting apparatus disclosed in Japanese Patent Unexamined Publication JP-A-2002-357410 has been proposed. According to the position detecting apparatus, a fluid delivered from a fluid supply source to a nozzle via a fixed throat is injected from an injecting hole at a front end of the nozzle to an inspection portion of a work or the like and a position of the inspection portion is detected by providing a nozzle back pressure.
On the other hand, an apparatus of measuring a hole diameter and a hole position of a work hole of a work worked by a tool disclosed in Japanese Patent Unexamined Publication JP-A-10-339623 has been proposed. According to the measuring apparatus, a measuring piece provided at a measuring instrument is inserted into a measured hole of a work set to a work positioning jig, and by injecting air from a plurality of injecting ports provided at a vicinity of a front end portion of the measuring piece in a direction orthogonal to a longitudinal direction of the measuring piece, respective back pressure of air are detected. Further, the hole diameter of the measured hole is calculated and a center position of the measured hole is calculated by calculating distances from the respective air injecting ports to an inner peripheral face of the work hole.
However, according to the position detecting apparatus of the JP-A-2002-357410, there poses a problem that although the position of the measured portion of the work or the like can be detected, a surface shape of a measured object cannot be measured.
Further, according to the apparatus of measuring the hole diameter and the hole position of the JP-A-10-339623, there is constructed a constitution of inserting the measuring piece into the measured hole. Therefore, there poses a problem that measuring operation is troublesome, measuring time is prolonged. Further, it is difficult to follow a change in the hole diameter and furthermore, it is difficult to apply to the work hole having a small hole diameter.